Polarizer with Composite Materials

ABSTRACT

It would be advantageous to improve polarizer high temperature resistance, corrosion resistance, oxidation resistance, optical properties, and etchability. Composite polarizer materials can be used to achieve this. A polarizer can comprise polarization structures configured for polarization of light. The polarization structures can include a reflective rib, the reflective rib being a composite of two different elements. The polarization structures can include an absorptive rib, the absorptive rib being a composite of two different elements. The polarizer can include a transparent layer, the transparent layer being a composite of two different elements.

CLAIM OF PRIORITY

This is a continuation application of U.S. patent application Ser. No.16/929,457, filed on Jul. 15, 2020, which claims priority to U.S.Provisional Patent Application No. 62/879,947, filed on Jul. 29, 2019,which are incorporated herein by reference.

FIELD OF THE INVENTION

The present application is related generally to polarizers.

BACKGROUND

There are many desirable characteristics of polarizer materials. Thesecharacteristics include a narrow range of optical properties, such asreflectance R, refractive index n, extinction coefficient k, andelectrical resistivity. Nanometer-sized polarization structures aretypically formed by etching, so etchability can be another desirablecharacteristic.

Polarizers are used in image projectors. Brighter and smaller projectorshave resulted in increased polarizer temperature, and resultingdeformation or melting of polarizer components. Consequently, it wouldalso be useful for polarizers to be able to withstand highertemperatures.

Polarization structures can be small and delicate with nanometer-sizedpitch, wire-width, and wire-height. Polarizers are used in systems (e.g.image projectors, semiconductor inspection tools, etc.) that requirehigh performance. Small defects in the polarizer, such as corroded ribsor collapsed ribs can significantly degrade system performance (e.g.distorted image from a computer projector). Oxidation of the ribs candegrade system performance by adversely affecting contrast. Therefore,it can be useful to protect the ribs or other polarization structuresfrom corrosion and oxidation.

SUMMARY

It has been recognized that it would be advantageous to improvepolarizer optical properties, etchability, high temperature resistance,corrosion resistance, and oxidation resistance. The present invention isdirected to various embodiments of polarizers that satisfy these needs.Each embodiment may satisfy one, some, or all of these needs. Thepolarizer can include a reflective rib, an absorptive rib, a transparentlayer, or combinations thereof, each being a composite of two differentelements.

BRIEF DESCRIPTION OF THE DRAWINGS (DRAWINGS MIGHT NOT BE DRAWN TO SCALE)

FIG. 1 is a schematic, cross-sectional side-view of a polarizer 10,including polarization structures 12 configured for polarization oflight, in accordance with an embodiment of the present invention.

FIG. 2 is a schematic perspective-view of polarizer 10, in accordancewith an embodiment of the present invention.

FIG. 3 is a schematic, cross-sectional side-view of a polarizer 30,including polarization structures 12 configured for polarization oflight, a thin film 32 between the polarization structures 12 and thesubstrate 11, and a thin film 33 on an opposite side 11 _(o) of thesubstrate 11 from the polarization structures 12, in accordance with anembodiment of the present invention.

FIG. 4 is a schematic, cross-sectional side-view of a polarizer 40,including polarization structures 12 configured for polarization oflight, in accordance with an embodiment of the present invention.

FIG. 5 is a schematic, top-view of polarizer 40, in accordance with anembodiment of the present invention.

FIG. 6 is a schematic, cross-sectional side-view of a polarizer 60,including polarization structures 12 configured for polarization oflight, a thin film 32 between the polarization structures 12 and thesubstrate 11, and a thin film 33 on an opposite side 11 _(o) of thesubstrate 11 from the polarization structures 12, in accordance with anembodiment of the present invention.

FIG. 7a is a schematic, cross-sectional side-view of a polarizer 70 a,including: polarization structures 12 configured for polarization oflight; a channel 13 between adjacent polarization structures 12; and athin film 71 at a distal end 12 _(d) of the polarization structures 12,spanning the channels 13 and leaving the channels air-filled; inaccordance with an embodiment of the present invention.

FIG. 7b is a schematic, cross-sectional side-view of a polarizer 70 b,including polarization structures 12 configured for polarization oflight, a channel 13 between adjacent polarization structures 12, and athin film 72 at a distal end 12 _(d) of the polarization structures 12and filling the channels 13, in accordance with an embodiment of thepresent invention.

FIG. 7c is a schematic, cross-sectional side-view of a polarizer 70 c,including polarization structures 12 configured for polarization oflight, and multiple thin films 73 and 74 at a distal end 12 _(d) of thepolarization structures 12, in accordance with an embodiment of thepresent invention.

FIG. 7d is a schematic, cross-sectional side-view of a polarizer 70 d,including polarization structures 12 configured for polarization oflight, and a thin film 75 as a conformal coating along sides 12 _(s) ofand at the distal end 12 _(d) of the polarization structures 12, andalso along exposed parts of the substrate 11, in accordance with anembodiment of the present invention.

FIG. 8 is a schematic, cross-sectional side-view of continuous thin-film31, including repeated thin film pairs 83, in accordance with anembodiment of the present invention.

FIG. 9a is a schematic, cross-sectional side-view of a polarizer 90 a,including polarization structures 12 configured for polarization oflight, the polarization structures 12 including a reflective rib 91, inaccordance with an embodiment of the present invention.

FIG. 9b is a schematic, cross-sectional side-view of a polarizer 90 b,including polarization structures 12 configured for polarization oflight, the polarization structures 12 including a dielectric rib 92, inaccordance with an embodiment of the present invention.

FIG. 9c is a schematic, cross-sectional side-view of a polarizer 90 c,including polarization structures 12 configured for polarization oflight, the polarization structures 12 including multiple dielectric ribs92, in accordance with an embodiment of the present invention.

FIG. 9d is a schematic, cross-sectional side-view of polarizer 90 d,including polarization structures 12 configured for polarization oflight, the polarization structures 12 including a reflective rib 91 anda dielectric rib 92, in accordance with an embodiment of the presentinvention.

FIG. 9e is a schematic, cross-sectional side-view of polarizer 90 e,including polarization structures 12 configured for polarization oflight, the polarization structures 12 including a reflective rib 91sandwiched between a pair of dielectric ribs 92, in accordance with anembodiment of the present invention.

DEFINITIONS

As used herein, “Al” means aluminum, “Ag” means silver, “Au” means gold,“B” means boron, “C” means carbon, “Ce” means cerium, “Cr” meanschromium, “Ge” means germanium, “Hf” means hafnium, “Mg” meansmagnesium, “Mo” means molybdenum, “Nb” means niobium, “Nd” meansneodymium, “Ni” means nickel, “Pt” means platinum, “Sc” means scandium,“Si” means silicon, “Ta” means tantalum, “Th” means thorium, “Ti” meanstitanium, and “W” means tungsten.

Metal and metalloid oxides, nitrides, and fluorides listed herein,include the common stoichiometric combination, plus other combinations,including nonstoichiometric combinations.

As used herein, the term “composite” means a mixture, alloy, or compoundof multiple elements or materials.

As used herein, the term “continuous”, as in “continuous thin film”,means that the thin film is not divided into separate grid or wires.

As used herein, the term “elongated” means that a length L₁₂ of thepolarization structures 12 is substantially larger than polarizationstructure 12 width W₁₂, thickness Th₁₂, or pitch P. For example, thelength L₁₂ can be ≥10 times, ≥100 times, ≥1000 times, or ≥10,000 timeslarger than the W₁₂, the thickness Th₁₂, the pitch P, or combinationsthereof. Polarization structure Wiz, thickness Th₁₂, and pitch P canhave nanometer dimensions (i.e. all <1 micrometer), but length L₁₂ canhave millimeter dimensions (i.e. >1 mm).

As used herein, the term “evenly”, with regard to a mixture ofmaterials, means exactly even, even within normal manufacturingtolerances, or nearly even, such that any deviation from exactly evenwould have negligible effect for ordinary use of the device.

As used herein, the term “fill the channels” means completely filled,filled within normal manufacturing tolerances, or almost completelyfilled, such that any deviation from completely filled would havenegligible effect for ordinary use of the device.

As used herein, the terms “metal” and “metals” do not includemetalloid(s).

As used herein, the terms “on” and “located on” mean located directly onor located above with some other solid material between.

As used herein, the term “mm” means millimeter(s) and the term “nm”means nanometer(s).

As used herein, the term “ohm*m” means ohms times meters, units forelectrical resistivity.

Materials used in optical structures can absorb some light, reflect somelight, and transmit some light. The following definitions distinguishbetween materials that are primarily absorptive, primarily reflective,or primarily transparent. Each material can be considered to beabsorptive, reflective, or transparent in a wavelength range of intendeduse, across the ultraviolet spectrum (≥10 nm & <400 nm), across thevisible spectrum (≥400 nm & <700 nm), across the infrared spectrum (≥700nm ≤1 mm), or combinations thereof, and can have a different property ina different wavelength range. Thus, whether a material is absorptive,reflective, or transparent is dependent on the intended wavelength rangeof use. Materials are divided into absorptive, reflective, andtransparent based on reflectance R, the real part of the refractiveindex n, and the imaginary part of the refractive index/extinctioncoefficient k. Equation 1 is used to determine the reflectance R of theinterface between air and a uniform slab of the material at normalincidence:

$\begin{matrix}{R = \frac{\left( {n - 1} \right)^{2} + k^{2}}{\left( {n + 1} \right)^{2} + k^{2}}} & {{Equation}\mspace{11mu} 1}\end{matrix}$

Unless explicitly specified otherwise herein, materials with k≤0.1 inthe wavelength range are “transparent” materials, materials with k>0.1and R≤0.6 in the specified wavelength range are “absorptive” materials,and materials with k>0.1 and R>0.6 in the specified wavelength range are“reflective” materials. If explicitly so stated in the claims, materialswith k>0.1 and R≥0.7, R≥0.8, or R≥0.9, in the specified wavelengthrange, are “reflective” materials.

Unless explicitly noted otherwise herein, all temperature-dependentvalues are such values at 25° C.

DETAILED DESCRIPTION Polarization Structures 12

As illustrated in FIGS. 1-6, polarizers 10, 30, 40, and 60 are showncomprising polarization structures 12. The polarization structures 12can be located on a substrate 11. The polarization structures 12 can beconfigured for polarization of light.

As illustrated in FIGS. 1-3, the polarization structures 12 can be anarray of wires with a channel 13 between adjacent wires. The array ofwires can be parallel and elongated.

As illustrated in FIGS. 4-6, the polarization structures 12 can be ametamaterial polarizer. For polarizers 40 and 60, a longitudinaldimension of some of the polarization structures 12 can extend in afirst direction D1, a longitudinal dimension of other of thepolarization structures 12 can extend in a second direction D2, and thefirst direction D1 can be a different direction from the seconddirection D2. The first direction D1 can be perpendicular to the seconddirection D2. The polarization structures 12 of polarizers 40 and 60 canhave multiple thicknesses Th₁₂, such as for example ≥2 thicknesses Th₁₂,≥3 thicknesses Th₁₂, ≥4 thicknesses Th₁₂, or ≥5 thicknesses Th₁₂. Eachthickness difference can be at least 10% different with respect to otherthicknesses Th₁₂.

Continuous Transparent Layers

As illustrated in FIGS. 3 and 6, the substrate 11 can be a continuousstructure (not interrupted to form a grid) and can be a compositetransparent layer with properties as described below. Example minimumthicknesses Thu of the substrate 11 include Th₁₁≥0.1 mm, Th₁₁≥0.4 mm, orTh₁₁≥0.6 mm.

As illustrated in FIGS. 3 and 6-8, the polarizers can have propertiessimilar to polarizers 10 and 40 described above, but further comprisingcontinuous thin-film(s) 31. The continuous thin-film(s) 31 can betransparent layer(s) with properties as described below. As illustratedin FIGS. 3 and 6, the continuous thin-film 31 can be a thin film 32between the polarization structures 12 and the substrate 11, a thin film33 on an opposite side 11 _(o) of the substrate 11 from the polarizationstructures 12, or both. As illustrated in FIGS. 7a-7d , the continuousthin-films 31 can be thin films 71, 72, 73, 74, and 75 at a distal end12 _(d) of the polarization structures 12 farthest from the substrate11. Thin-films 32, 33, or both can be combined with any of thin films71, 72, 73, 74, and 75.

As illustrated in FIG. 7a , thin film 71 can span the channels 13 andcan leave the channels air-filled. As illustrated in FIG. 7b , thin film72 can fill the channels 13. As illustrated in FIG. 7c , thin film 73can partially fill the channels 13, and a remainder of the channels 13can be air filled.

Also illustrated in FIG. 7c , there can be multiple thin films 73 and 74at the distal end 12 _(d) of the polarization structures 12. Thin film73 can be a lower continuous thin film between the substrate 11 and theupper continuous thin film, thin film 74. Thin film 74 can be applied onthin films 72 or 73. An upper continuous thin film, thin film 74, can beadded above thin film 71 or thin film 72.

Thin films 71-74 can provide structural support for the polarizationstructures 12, can protect the polarization structures 12 from handling,dust, or corrosion, can be used as a heat sink to draw heat away fromthe polarization structures 12, can be used to improve polarizerperformance, or combinations thereof. A choice between polarizers 70a-70 c can be made based on desired index of refraction in the channelsand whether protection of the polarization structures 12 in the channels13 is needed. Example thicknesses Th₇₁, Th₇₂, Th₇₃, and Th₇₄ of thinfilms 71, 72, 73, and 74, respectively, include ≥10 nm, ≥50 nm, or ≥100nm; and ≤100 nm, ≤250 nm, ≤500 nm, or ≤1000 nm.

As illustrated in FIG. 7d , thin film 75 can be a conformal coatingalong sides 12 _(s) of and at the distal end 12 _(d) of the polarizationstructures 12, and also along exposed parts of the substrate 11. Thinfilm 75 can protect the polarization structures 12 from corrosion,oxidation, or both. Example thicknesses Th₇₅ of thin film 75 include≥0.5 nm, ≥1 nm, or ≥5 nm; and ≤5 nm, 10 nm, ≤20 nm, or ≤30 nm. Thin film75 can be combined with thin films 32, 33, 71, 72, 73, 74, orcombinations thereof.

As illustrated in FIG. 8, the continuous thin-film 31 can be repeatedthin film pairs 83 (e.g. ≥2 pairs, ≥3 pairs, or ≥4 pairs,). Each of thethin film pairs 83 can include a high index layer 81 and a low indexlayer 82. Either the high index layer 81 or the low index layer 82 canbe closest to the substrate 11. It can be preferable, however, to havethe high index layer 81 closest to the substrate 11, the low index layer82 as an outermost layer (i.e. outermost of the high index layers 81 andthe low index layers 82), or both, for protection of the high indexlayer 81.

The high index layer 81, the low index layer 82, or both can becomposites of two different elements, as described below. The high indexlayer 81 can have an index of refraction n≥1.8, n≥1.9, n≥2, n≥2.2, orn≥2.4 and an extinction coefficient k≤0.1. The low index layer 82 canhave index of refraction n≤1.4, n≤1.5, n≤1.6, n≤1.7, or n≤1.8 and anextinction coefficient k≤0.1. The indices of refraction and extinctioncoefficients of this paragraph are such values across the ultravioletspectrum, the visible spectrum, the infrared spectrum, or combinationsthereof.

Reflective Rib 91 and Dielectric Rib 92

Illustrated in FIGS. 9a-9e , and described below, are examplecharacteristics of the polarization structures 12. These characteristicscan be applied to any of the polarizer embodiments described herein. Thepolarization structures 12 can include reflective rib(s) 91, dielectricrib(s) 92, or combinations thereof. Each reflective rib 91 can be acomposite as described below. Each dielectric rib 92 can be anabsorptive rib or a transparent rib, and can be a composite as describedbelow.

The polarization structures 12 of polarizer 90 a in FIG. 9a comprise areflective rib 91. Only a single reflective rib 91 is illustrated inFIG. 9a , but the polarizer 90 a can include additional reflective ribs91 in each polarization structure 12. The polarization structures 12 ofpolarizer 90 b in FIG. 9b comprise a dielectric rib 92, which can be anabsorptive rib or a transparent rib.

The polarization structures 12 of polarizer 90 c in FIG. 9c comprise twodielectric ribs 92, each of which can be an absorptive rib or atransparent rib. Thus, polarizer 90 c can include two absorptive ribs,two transparent ribs, or an absorptive rib and a transparent rib. Onlytwo dielectric ribs 92 are illustrated in FIG. 9c , but the polarizer 90c can include additional absorptive rib(s), additional transparentrib(s), reflective rib(s) 91, or combinations thereof, in eachpolarization structure 12.

The polarization structures 12 of polarizer 90 d in FIG. 9d eachcomprise a reflective rib 91 and a dielectric rib 92. The dielectric rib92 can be an absorptive rib or a transparent rib. Although thereflective rib 91 is illustrated as closer to the substrate 11 in FIG.9d , the opposite configuration is also within the scope of theinventions herein, with the dielectric rib 92 closer to the substrate11.

The polarization structures 12 of polarizer 90 e in FIG. 9e comprise areflective rib 91 sandwiched between a pair of dielectric ribs 92. Eachdielectric rib 92 can be an absorptive rib or a transparent rib. Thus,polarizer 90 e can include two absorptive ribs, two transparent ribs, oran absorptive rib and a transparent rib. If the two dielectric ribs 92in FIG. 9e are an absorptive rib and a transparent rib, either theabsorptive rib or the transparent rib can be the dielectric rib 92closest to the substrate 11, and the other farthest from the substrate11.

A choice between the embodiments of FIGS. 90a-90e can be made based onpolarizer application and wavelength range of polarization.

Composite Reflective

The reflective rib 91 can be a composite of at least two differentelements, defining reflective rib elements. Material of the reflectiverib 91 can be homogeneous throughout. The reflective rib elements can bespread evenly throughout the reflective rib 91. Use of a composite canimprove polarizer high temperature resistance, corrosion resistance,oxidation resistance, or combinations thereof.

For example, aluminum has traditionally been used as the reflective ribin wire grid polarizers. These polarizers are often used in projectors.The thin aluminum ribs/wires can deform at temperatures around 400° C.and melt at 660° C. Wire grid polarizers in image projectors have failedin this manner. Although aluminum is thought of as being corrosionresistant, it does corrode a small amount, and with wires having a widthof around 60 nm, any small amount of corrosion can ruin the wire. Asanother example, the aluminum wire can change in size due to oxidationat an outer surface, converting reflective aluminum into transparentaluminum oxide, with vastly different optical properties.

Aluminum, silver, or both can be combined with other elements) in acompound in order to improve on the above properties. Alternatively,aluminum, silver, or both can be replaced entirely with differentchemical elements. An element susceptible to corrosion or oxidation(e.g. Al or Ag), can be combined with a chemical element more resistantto corrosion or oxidation (e.g. Au, Cr, Mo, Nd, Ni, Pt, Ti, W) to formthe reflective rib 91. Thus, for example, the reflective rib 91 can bemore resistant to corrosion (e.g. water corrosion), to oxidation, orboth, than pure aluminum or pure silver.

The reflective rib 91 can be a composite of Ti and W. A combined weightpercent of Ti and W in the reflective rib 91 can be ≥25%, ≥50%, ≥75%,≥90%, or ≥99%. If Ti and W don't constitute 100% of the reflective rib91, the remainder can be Al, Ag, Au, Cr, Mo, Nd, Ni, Pt, or combinationsthereof, or any other element.

The reflective rib 91 can be a composite of Al and Cr. A combined weightpercent of Al and Cr in the reflective rib 91 can be ≥25%, ≥50%, ≥75%,≥90%, or ≥99%. If Al and Cr don't constitute 100% of the reflective rib91, the remainder can be Ag, Au, Mo, Nd, Ni, Pt, Ti, W, or combinationsthereof, or any other element.

The reflective rib 91 can be a composite of Al and Ti. A combined weightpercent of Al and Ti in the reflective rib 91 can be ≥25%, ≥50%, ≥75%,90%, or ≥99%. If Al and Ti don't constitute 100% of the reflective rib91, the remainder can be Ag, Au, Cr, Mo, Nd, Ni, Pt, W, or combinationsthereof, or any other element.

The reflective rib 91 can be a composite of Al and Mo. A combined weightpercent of Al and Mo in the reflective rib 91 can be ≥25%, ≥50%, ≥75%,≥90%, or ≥99%. If Al and Mo don't constitute 100% of the reflective rib91, the remainder can be Ag, Au, Cr, Nd, Ni, Pt, Ti, W, or combinationsthereof, or any other element.

The reflective rib 91, with a lower melting point chemical element (e.g.Al), can withstand a higher temperature by adding higher melting pointchemical element(s) (e.g. Ag, Ce, Cr, Mo, Nb, Nd, Pt, Sc, Ta, Th, Ti,W). The reflective rib 91 as a composite can have a higher meltingpoint, such as for example ≥700° C., ≥800° C., ≥900° C., or ≥1000° C.

Following are example reflective rib 91 compositions. Reflective ribelements can include any combination of Al, Ag, Au, B, Ce, Cr, Mo, Nb,Nd, Ni, Pt, Sc, Ta, Th, Ti, W. Oxygen, nitrogen, fluorine, orcombinations thereof can be not counted as one of, the reflective ribelements. Each reflective rib element can have an atomic number 12. Thereflective rib elements can include metals, metalloids, or both. Thereflective rib elements can include Al or Ag with a mass percent in thereflective rib 91 of ≤85%, ≤90%, ≤95%, ≤98%, ≤99%, or ≤99.9%; and ≥0.1%,≥5%, ≥10%, ≥50%, ≥80%, or ≥85%.

The reflective rib elements can include Al plus one, two, or more thantwo elements other than Al. Example mass percentages of the non-aluminumchemical elements include ≥0.1%, ≥0.5%, ≥1%, or ≥5%; and ≤5%, ≤10%,≤20%, ≤50%, ≤70%, ≤90%, or ≤99.9%. Note that an outer edge of analuminum reflective rib 91 is a natural oxidation, aluminum oxide(Al₂O₃). Aluminum oxide is transparent, thus not part of the aluminumreflective rib 91 (i.e. it is transparent—not reflective). Therefore,the oxygen of aluminum oxide is not one of the reflective rib elements.

The reflective rib elements can include Ag plus one, two, or more thantwo elements other than Ag. Example mass percentages of the non-silverchemical elements include ≥0.1%, ≥0.5%, ≥1%, or ≥5%; and ≤5%, ≤10%,≤20%, ≤50%, ≤70%, ≤90%, or ≤99.9%.

Added factors to consider, in selection of reflective rib elements,include refractive index n, extinction coefficient k, etchability, andresistivity. The reflective rib 91 can have extinction coefficient k>0.1and reflectance R>0.6 at a wavelength range of intended use, across theultraviolet spectrum, across the visible spectrum, across the infraredspectrum, or combinations thereof. An equation for calculation of R islisted in the definitions section above. It can be helpful if allreflective rib elements are reflective materials. The reflective ribelements can each have k>0.1 and R>0.6 at a wavelength in theultraviolet spectrum, the visible spectrum, the infrared spectrum, orcombinations thereof. The reflective rib 91 can be electricallyconductive. For example, the reflective rib 91 can have resistivity≤10⁻⁴ ohm*m, ≤10⁻⁶ ohm*m, or ≤10⁻⁸ ohm*m.

A total percentage of all elements in the reflective rib is 100 masspercent.

Composite Absorptive

The absorptive rib(s) can each independently be a composite of at leasttwo different elements, defining absorptive rib elements.

All absorptive rib elements can be absorptive. Alternatively, theabsorptive rib elements can include an element that would normallyresult in a reflective structure if used by itself, but that results inan absorptive rib when combined with absorptive elements. For example,the absorptive rib(s) can include C, Ge, Si, Ta, or combinations thereof(absorptive elements), combined with Al, Ag, Au, B, Ce, Cr, Mo, Nb, Nd,Ni, Pt, Sc, Ta, Th, Ti, W, or combinations thereof (reflectiveelements). Normally, the absorptive rib(s) will include a small percentof the reflective elements and a large percent of the absorptiveelements. For example, the absorptive rib(s) can include:

≥0.01 mass percent, ≥0.1 mass percent, or ≥1 mass percent of thereflective element(s), and ≤1 mass percent, ≤10 mass percent, or ≤25mass percent of the reflective element(s);≥75 mass percent, ≥90 mass percent, ≥95 mass percent, or ≥99 masspercent of the absorptive element(s), and ≤90 mass percent, ≤95 masspercent, or ≤100 mass percent of the absorptive element(s); andthe mass percent of the reflective element(s) plus a mass percent of theabsorptive element(s) is ≥100 mass percent.

Oxygen, nitrogen, fluorine, or combinations thereof can be not countedas one of, the absorptive rib elements. Each absorptive rib element canhave an atomic number ≥14. The absorptive rib elements can be metals,metalloids, or both. The absorptive rib elements can include anycombination of C, Ge, Si, and Ta. The dielectric rib 92 can behomogeneous throughout. The absorptive rib elements can be spread evenlythroughout the dielectric rib 92.

Use of composite absorptive rib(s) can improve corrosion resistance andpolarizer performance. For example, a desirable characteristic ofabsorptive polarizers is reduced reflection (e.g. reduced Rs) of theprimarily-absorbed polarization. Germanium can be useful due to low Rs(better than silicon), but is also susceptible to corrosion. Agermanium-silicon composite can have good performance (like germanium)but with improved corrosion resistance. As another example, eachabsorptive material can have optimal performance at a specific, narrowwavelength range. Use of a composite of multiple, absorptive elementscan increase the range of optimal performance (i.e. improved broadbandperformance).

Following are example absorptive rib compositions. A mass percent ofeach of the absorptive rib elements in the absorptive rib can be ≥1%.The absorptive rib elements can include Ge with a mass percent in theabsorptive rib of ≤30%, ≤50%, ≤80%, ≤99%, or ≤99.9%; and ≥0.1%, ≥10%,≥20%, or ≥30%. The absorptive rib elements can include Si with a masspercent in the absorptive rib of ≤30%, ≤50%, ≤80%, ≤99%, or ≤99.9%; and≥0.1%, ≥10%, ≥20%, or ≥30%. The mass percent of Ge in the absorptive ribcan be greater than the mass percent of Si in the absorptive rib.

Added factors to consider, in selection of absorptive rib elements,include refractive index n, extinction coefficient k, and etchability.The absorptive rib 71 can have extinction coefficient k>0.1 andreflectance R≤0.6 at a wavelength range of intended use, across theultraviolet spectrum, the visible spectrum, the infrared spectrum, orcombinations thereof. An equation for calculation of R is listed in thedefinitions section above. It can be helpful if all absorptive ribelements are absorptive materials. The absorptive rib elements can eachhave k>0.1 and R≤0.6 at a wavelength in the ultraviolet spectrum, thevisible spectrum, the infrared spectrum, or combinations thereof.

A total mass percent of all elements in the absorptive rib is 100 masspercent.

Composite Transparent

The transparent layers described herein, which can be the substrate 11,the continuous thin-film 31, the transparent rib, or combinationsthereof, can be a composite of ≥2, ≥3, or ≥4 different elements,defining transparent layer elements.

Oxygen, fluorine, carbon, nitrogen, or combinations thereof can be notcounted as, transparent layer elements. Although oxygen, fluorine, andnitrogen might not be counted as transparent layer elements, they can beincluded in the transparent layer. For example, the transparent layercan include combinations of aluminum oxide, hafnium oxide, magnesiumfluoride, magnesium oxide, niobium oxide, sapphire, silicon dioxide,silicon nitride, silicon oxynitride, silicon carbide, titanium oxide,and zirconium oxide. Each transparent layer element can be a metal or ametalloid. Each transparent layer element can have an atomic number ≥12.Example transparent layer elements include Al, Hf, Mg, Nb, Si, Ti, Zr,transition metals, and lanthanide series metals.

Example minimum mass percentages of each of the transparent layerelements in the transparent layer include ≥0.01%, ≥1%, ≥10%, or ≥25%.Example maximum mass percentages of each of the transparent layerelements in the transparent layer include ≤99.5%, ≤99%, ≤90%, or ≤70%. Atotal percentage of all elements in the transparent layer is 100 masspercent.

The transparent layer can have k≤0.1, k≤0.01, or k≤0.001 across awavelength range of intended use, the ultraviolet spectrum, the visiblespectrum, the infrared spectrum, or combinations thereof. k is theextinction coefficient.

Material of the transparent layer can be homogeneous throughout thetransparent layer. The transparent layer elements are spread evenlythroughout the transparent layer.

Use of a composite as the transparent layer(s) can improve polarizercorrosion resistance, performance, durability, and high-temperatureresistance. Additional useful characteristics of the transparentlayer(s), which can be improved by use of a composite, include broadwavelength range transparency, increased thermal conductivity, increasedelectrical resistance, toughness, and the ability to polish.

For example, silicon dioxide can be useful due to its low refractiveindex n. Aluminum oxide can be useful due to its high coefficient ofthermal conductivity. A composite of these two materials can haveimproved overall properties. A mass percent of aluminum oxide in thetransparent layer can be greater than a mass percent silicon dioxide inthe transparent layer, in order to improve thermal conductivity.

How to Make

The composites described above can be made by sputter deposition. Asputter target can be selected that has the desired chemical elements inthe desired ratios. Alternatively, the desired chemical elements can bemixed in a colloidal suspension. Curing, or causing a chemical reactionin, the colloidal suspension can include evaporating or reacting asolvent.

What is claimed is:
 1. A polarizer comprising: polarization structures configured for polarization of light, the polarization structures including a reflective rib; k>0.1 and R>0.6 for the reflective rib across a visible spectrum of light, where reflectance R is calculated from: ${R = \frac{\left( {n - 1} \right)^{2} + k^{2}}{\left( {n + 1} \right)^{2} + k^{2}}},$ n is a real part of a refractive index, and k is an extinction coefficient; the reflective rib is a composite of two different elements, defining reflective rib elements, and the reflective rib elements include Al plus Mo, Ta, or both; and material of the reflective rib is homogeneous throughout the reflective rib and the reflective rib elements are spread evenly throughout the reflective rib.
 2. The polarizer of claim 1, wherein a mass percent of Al in the reflective rib ≥85%.
 3. The polarizer of claim 1, wherein the reflective rib elements include Mo, and a mass percent of Mo in the reflective rib is ≥0.5% and ≤10%.
 4. The polarizer of claim 1, wherein the reflective rib elements include Mo, and a mass percent of Mo in the reflective rib is ≥1% and ≤5%.
 5. A polarizer comprising: polarization structures configured for polarization of light, the polarization structures include a reflective rib; k>0.1 and R>0.6 for the reflective rib and k>0.1 and R≤0.6 for the absorptive rib across a visible spectrum of light, where reflectance R is calculated from: ${R = \frac{\left( {n - 1} \right)^{2} + k^{2}}{\left( {n + 1} \right)^{2} + k^{2}}},$ n is a real part of a refractive index, and k is an extinction coefficient; and the reflective rib is a composite of two different elements, defining reflective rib elements, and every reflective rib element is a metal.
 6. The polarizer of claim 5, wherein the reflective rib is more resistant to water corrosion, to oxidation, or both, than pure aluminum.
 7. The polarizer of claim 5, wherein the reflective rib has a melting point of ≥700° C.
 8. The polarizer of claim 5, wherein the reflective rib has a melting point of ≥800° C.
 9. The polarizer of claim 5, wherein the reflective rib has a melting point of ≥900° C.
 10. A polarizer comprising: polarization structures on a substrate configured for polarization of light; a transparent layer being a composite including two different elements, defining transparent layer elements, oxygen, nitrogen, and fluorine not counted as transparent layer elements; and the transparent layer is a transparent rib in the polarization structures or a continuous thin film located at a distal end of the polarization structures farthest from the substrate.
 11. The polarizer of claim 10, wherein the transparent layer is a transparent rib in the polarization structures.
 12. The polarizer of claim 10, wherein the transparent layer is located at a distal end of the polarization structures farthest from the substrate.
 13. The polarizer of claim 10, wherein each transparent layer element is a metal or a metalloid.
 14. The polarizer of claim 10, wherein each transparent layer element has an atomic number ≥12.
 15. The polarizer of claim 10, wherein: the transparent layer elements include two of magnesium, silicon, and titanium; and the transparent layer includes two of magnesium fluoride, silicon dioxide, and titanium oxide.
 16. The polarizer of claim 10, wherein a mass percent of each of the transparent layer elements in the transparent layer is ≥1%.
 17. The polarizer of claim 10, wherein material of the transparent layer is homogeneous throughout the transparent layer and the transparent layer elements are spread evenly throughout the transparent layer.
 18. The polarizer of claim 10, wherein: the polarization structures include repeating thin film pairs; each of the thin film pairs include a high index layer with an index of refraction n≥1.8 and an extinction coefficient k≤0.1, and a low index layer with an index of refraction n≤1.6 and an extinction coefficient k≤0.1, across the ultraviolet spectrum, the visible spectrum, or both; the transparent layer is the low index layer; and the high index layer is a composite of two different elements, defining transparent layer elements, oxygen, nitrogen, and fluorine are not counted as transparent layer elements.
 19. The polarizer of claim 18, wherein the repeating thin film pairs include three pairs.
 20. The polarizer of claim 18, wherein the high index layer is closest to the substrate and the low index layer is an outermost layer of the thin film pairs. 